Problem: Simplify the following expression: $y = \dfrac{p - 9}{2p - 9} \div \dfrac{1}{4}$
Solution: Dividing by a number is the same as multiplying by its inverse. $y = \dfrac{p - 9}{2p - 9} \times \dfrac{4}{1}$ When multiplying fractions, we multiply the numerators and the denominators. $y = \dfrac{(p - 9) \times 4} {(2p - 9) \times 1}$ $y = \dfrac{4p - 36}{2p - 9}$